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f1f5ec1efa
When processing ordered aggregates following a sort that could make use of the abbreviated key optimization, only call the equality operator to compare successive pairs of tuples when their abbreviated keys were not equal. Peter Geoghegan, reviewd by Andreas Karlsson and by me.
126 lines
4.9 KiB
C
126 lines
4.9 KiB
C
/*-------------------------------------------------------------------------
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*
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* tuplesort.h
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* Generalized tuple sorting routines.
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*
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* This module handles sorting of heap tuples, index tuples, or single
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* Datums (and could easily support other kinds of sortable objects,
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* if necessary). It works efficiently for both small and large amounts
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* of data. Small amounts are sorted in-memory using qsort(). Large
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* amounts are sorted using temporary files and a standard external sort
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* algorithm.
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*
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* Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/utils/tuplesort.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef TUPLESORT_H
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#define TUPLESORT_H
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#include "access/itup.h"
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#include "executor/tuptable.h"
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#include "fmgr.h"
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#include "utils/relcache.h"
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/* Tuplesortstate is an opaque type whose details are not known outside
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* tuplesort.c.
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*/
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typedef struct Tuplesortstate Tuplesortstate;
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/*
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* We provide multiple interfaces to what is essentially the same code,
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* since different callers have different data to be sorted and want to
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* specify the sort key information differently. There are two APIs for
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* sorting HeapTuples and two more for sorting IndexTuples. Yet another
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* API supports sorting bare Datums.
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*
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* The "heap" API actually stores/sorts MinimalTuples, which means it doesn't
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* preserve the system columns (tuple identity and transaction visibility
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* info). The sort keys are specified by column numbers within the tuples
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* and sort operator OIDs. We save some cycles by passing and returning the
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* tuples in TupleTableSlots, rather than forming actual HeapTuples (which'd
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* have to be converted to MinimalTuples). This API works well for sorts
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* executed as parts of plan trees.
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*
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* The "cluster" API stores/sorts full HeapTuples including all visibility
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* info. The sort keys are specified by reference to a btree index that is
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* defined on the relation to be sorted. Note that putheaptuple/getheaptuple
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* go with this API, not the "begin_heap" one!
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*
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* The "index_btree" API stores/sorts IndexTuples (preserving all their
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* header fields). The sort keys are specified by a btree index definition.
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*
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* The "index_hash" API is similar to index_btree, but the tuples are
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* actually sorted by their hash codes not the raw data.
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*/
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extern Tuplesortstate *tuplesort_begin_heap(TupleDesc tupDesc,
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int nkeys, AttrNumber *attNums,
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Oid *sortOperators, Oid *sortCollations,
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bool *nullsFirstFlags,
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int workMem, bool randomAccess);
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extern Tuplesortstate *tuplesort_begin_cluster(TupleDesc tupDesc,
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Relation indexRel,
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int workMem, bool randomAccess);
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extern Tuplesortstate *tuplesort_begin_index_btree(Relation heapRel,
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Relation indexRel,
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bool enforceUnique,
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int workMem, bool randomAccess);
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extern Tuplesortstate *tuplesort_begin_index_hash(Relation heapRel,
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Relation indexRel,
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uint32 hash_mask,
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int workMem, bool randomAccess);
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extern Tuplesortstate *tuplesort_begin_datum(Oid datumType,
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Oid sortOperator, Oid sortCollation,
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bool nullsFirstFlag,
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int workMem, bool randomAccess);
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extern void tuplesort_set_bound(Tuplesortstate *state, int64 bound);
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extern void tuplesort_puttupleslot(Tuplesortstate *state,
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TupleTableSlot *slot);
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extern void tuplesort_putheaptuple(Tuplesortstate *state, HeapTuple tup);
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extern void tuplesort_putindextuplevalues(Tuplesortstate *state,
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Relation rel, ItemPointer self,
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Datum *values, bool *isnull);
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extern void tuplesort_putdatum(Tuplesortstate *state, Datum val,
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bool isNull);
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extern void tuplesort_performsort(Tuplesortstate *state);
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extern bool tuplesort_gettupleslot(Tuplesortstate *state, bool forward,
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TupleTableSlot *slot, Datum *abbrev);
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extern HeapTuple tuplesort_getheaptuple(Tuplesortstate *state, bool forward,
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bool *should_free);
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extern IndexTuple tuplesort_getindextuple(Tuplesortstate *state, bool forward,
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bool *should_free);
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extern bool tuplesort_getdatum(Tuplesortstate *state, bool forward,
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Datum *val, bool *isNull, Datum *abbrev);
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extern bool tuplesort_skiptuples(Tuplesortstate *state, int64 ntuples,
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bool forward);
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extern void tuplesort_end(Tuplesortstate *state);
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extern void tuplesort_get_stats(Tuplesortstate *state,
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const char **sortMethod,
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const char **spaceType,
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long *spaceUsed);
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extern int tuplesort_merge_order(int64 allowedMem);
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/*
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* These routines may only be called if randomAccess was specified 'true'.
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* Likewise, backwards scan in gettuple/getdatum is only allowed if
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* randomAccess was specified.
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*/
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extern void tuplesort_rescan(Tuplesortstate *state);
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extern void tuplesort_markpos(Tuplesortstate *state);
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extern void tuplesort_restorepos(Tuplesortstate *state);
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#endif /* TUPLESORT_H */
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